1. Technical Field
This invention generally relates to optical devices, and more specifically relates to optical devices and methods that are formed from multiple objects.
2. Background Art
Modern projection screens have been developed that provide greater than unity gain by including multiple convex and/or concave elements in an array. For example, one known configuration includes an array of small square elements. Each of the square elements are reflective, and are formed into a convex shape to reflect projected light in a manner that improves the optical characteristics of the screen by enhancing the fraction of projected light directed towards viewers and reducing the fraction of reflected ambient light directed towards the viewers.
One problem with known methods for forming such arrays of elements is the cost and technical difficulty of achieving an array that has selectable or consistent effective curvatures between elements. Further, the resulting screens are not able to provide high gain and/or sharp angular cut-off. The sharp angular cut-off is particularly important for rejecting background light impinging from off axis and for allowing the overlay of multiple, angularly separable images.